Double Diffusion Design for High-Performance NPN Transistors
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Summary
Problems
Conventional semiconductor devices face challenges in achieving desired high frequency characteristics and current amplification factors while maintaining breakdown voltage characteristics, as the formation of high-concentration active base regions with small diffusion depths compromises breakdown voltage, and low-concentration internal base regions with large diffusion depths increase base resistance, making it difficult to achieve optimal performance in NPN transistors.
Innovation solutions
A semiconductor device with a double diffusion structure in the base region, where a first diffusion layer of one conductivity type is used as the base and a second diffusion layer of opposite conductivity type is used as the collector, allowing for improved high frequency characteristics and current amplification while maintaining breakdown voltage characteristics, and this structure is formed in the same step to reduce manufacturing costs and mask usage.
TRIZ Analysis
Specific contradictions:
General conflict description:
Principle concept:
If a high-concentration active base region with small diffusion depth is formed to improve high frequency characteristics and current amplification factor, then high frequency characteristics and current amplification factor are improved, but breakdown voltage characteristics deteriorate
Why choose this principle:
The base region is segmented into two distinct diffusion layers: a first diffusion layer providing high concentration at the surface for low resistance and high frequency performance, and a second diffusion layer providing lower concentration at greater depth for adequate breakdown voltage. This segmentation allows each layer to independently optimize for its specific function without compromising the other.
Principle concept:
If a high-concentration active base region with small diffusion depth is formed to improve high frequency characteristics and current amplification factor, then high frequency characteristics and current amplification factor are improved, but breakdown voltage characteristics deteriorate
Why choose this principle:
Different regions of the base diffusion structure are assigned different impurity concentrations tailored to local requirements. The surface region (first diffusion layer) has high impurity concentration to minimize base resistance and improve high frequency characteristics, while the deeper region (second diffusion layer) has lower impurity concentration to maintain adequate breakdown voltage characteristics.
Application Domain
Data Source
AI summary:
A semiconductor device with a double diffusion structure in the base region, where a first diffusion layer of one conductivity type is used as the base and a second diffusion layer of opposite conductivity type is used as the collector, allowing for improved high frequency characteristics and current amplification while maintaining breakdown voltage characteristics, and this structure is formed in the same step to reduce manufacturing costs and mask usage.
Abstract
In a semiconductor device of the present invention, an N type epitaxial layer is formed on a P type silicon substrate. In the epitaxial layer, P type diffusion layers as a base region, N type diffusion layers as collector regions and an N type diffusion layer as an emitter region are formed. In this event, the P type diffusion layers are formed so as to have a double diffusion structure, and an impurity concentration in a surface of the base region and in a region adjacent thereto is set high. This structure enables improvement in high frequency characteristics and in a current amplification factor while maintaining breakdown voltage characteristics of an NPN transistor.